Impregnated material and process of producing same



Patented Nov. 3, 1925.

UNITED STATES KIRK BROWN, OF MONTCLAIR, NEW JERSEY, ASSIGNOR TO BAKELITECORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

IMPREGNATED MATERIAL AND PROCESS OF PRODUCING SAME.

No Drawing.

To (.ZZ whom it 'nulg concern.

Be it known that I, KIRK BRowN, a citizen of the United States,andresident of Montclair, in the county of Essex and State of New Jersey,have invented certain new and useful Improvements in ImpregnatedMaterials and Processes of Producing Same, of which the following is aspecification.

The invention relates to impregnated material and process of producingthe same, and particularly to a fibrous material, preferably of thelaminated cardboard type, impregnated with a phenolic condensationproduct, and a process of producing the same.

Such products are used in the manufacture of a large variety ofarticles, such as gears and gear blanks, insulating parts, etc.Important uses of the product require that it shall be readily punched,drilled, sheared and otherwise mechanically worked. It is also importantfor many uses that it should be thoroughly water-resistant.

Such material is commonly strongly impregnated with phenolic resins andchemically reacted throughout by the application of heat to a hard,infusible and insoluble condition, to make it thoroughly water-resistantand to give it other desired properties. In such case, however, itcannot readily be operated upon mechanically. The usual method ofsecuring the easy working property is to utilize a considerably lessproportion of phenolic resin or impregnating material, that is, toreduce the proportion of impregnating or binding material to the fibrousor cellular base, either throughout the body or in any desired portionthereof. The water resistance of the product is, however, decreased bysuch reduction.

Another method of obtaining easy working properties is to limit thereaction of the condensation product, so that it does not thoroughlyharden. This, however, requires a nicety of control with respect totemperature and time. To make sure that the reaction is not carried toofar towards the complete hardness and infusibility which will beproduced by the full reaction, adds to the difliculty of manufacture,and increases cost. The process is not easily performed, since the timerequired will be different in accordance with variations of temperatureused, and in accordance with Application filed April 18, 1923. SerialNo. 633,015.

the mass of the work being treated. Another disadvantage of this processis that the outer surface as well as the interior portion, are notbrought to the hardened infusible stage and are therefore, lacking infinish and appearance and the electrical property known as surfaceresistivity. This defect is obviated by my invention.

These difliculties are overcome by the present invention, the product ofwhich has the property of being readily machined while being at the sametime water-resistant throughout. This is accomplished by impregnatingthe whole body with a suflicient proportlon of phenolic condensationprod not to produce the water-resistant quality throughout, thecondensation product in the exterior portion containing, however, agreater proportion of the methylene-conta1n1ng body, or hardeningingredient, in proportion to the phenol or equivalent in thecomposition, than is the case with the condensation product in theinterior. By this means the finished impregnated mass will have a hardouter covering or shell, which may be quite fully infusible and whichwill provide a fine finish for the product, the hard outer shell being,however, of insuflicient thickness to interfere with easy workingproperty of the product, the interior or main body portion of the massbeing considerably softer and more readily machined than the exteriorportion. In its preferred form such a product is formed of superposedlaminations orsheets of fibrous material substantially saturatedthroughout with the phenolic condensation product which is substantiallyfully reacted throughout, but is, as stated, of greater hardness on theexterior than in the interior because of the greater proportion ofmethylene-containing or other hardening reagent .in the condensationproduct with which the outer portion is impregnated.

The object of the invention is the pro.- duction of products of thecharacter referred to as articles of manufacture and the production of asuitable process by completed, so as to render the materialwater-impervious. The impregnating ma terial for these sheets containsformaldehyde, or other methylene-containing substances, or otherequivalent hardening reagent in such a proportion that the condensationproduct Wlll not harden to the same degree that it would if a greaterproportion of the hardening agent were in cluded, the sheets soimpregnated being intended, as stated, for the main body portion, orinterior of the mass. The sheetswhich are to form the exterior surfaceor surfaces of thelaminated roduct are thoroughly impregnated with sustances capable of reaction to produce a phenolic condensation productin which the methylene-containing, or hardening ingredient is resent inreater relative quantity and is oreferabl" present in proper proportionto yield a hard and fully reacted phenolic condensation product. Theimpregnated sheets are superposed one upon the other with the sheet orsheets containing the larger roportion of hardening reagent at the outerside or sides, the mass is consolidated and final reaction is caused inthe usual way by application of sufficient heat and pressure.

The impregnating material may comprise in each case mixtures of fusiblephenolic resins with an added percentage of hardening reagent, such, forexample, as hexamethylenetetramin, or it may comprise partial reactionproducts containing the desired proportions of aldehyde ormethylene-containing body or other hardening agent, ca-

' pable of transformation, onapplication of heat, to form a harder moreinfusible procluct, or it-may comprise phenol and formaldehyde or thelike original elements in proper proportions to form the desiredcondensation products. Likewise the invention is'not limited in any wayto any particular manner in which the fibrous material or base isimpregnated with the binding materials.

As an example of one way in which the invention may be practiced thelaminations or sheets which are to form the outside surfaces of theproduct may be saturated with a solution in alcohol or other appropriatesolvent of a fusible phenol resin and a proortion ofhexamethylenetetramin in suitable quantity to react with the fusiblephenol resin on a lication of heat in the usual way to transform themass into the hard infusible condition. The final condensation productformed by reaction of'the phenol a harder and more fusible product.

resin and the hcxamethylenetetramin may be that or similar to thatdescribed in patent to J. \V. Aylsworth N 0. 1,020,593, March 19, 1912,a solution of such a fusible phenol resin and hardening agent thereforin a suitable solvent being described in the patent to J. V. AylsworthNo. 1,098,608, granted June 2, 1914. The laminations which are to formthe main body or interior of the laminated mass may similarly hesaturated with a solution, in alcohol or other appropriate solvent ofthe fusible phenol resin and hexamethylenetetramin, the latter inapproximately one-half the proportion which is used in impregnating theoutside sheets, or in any other desired proportion, according to theparticular effects required. The sheets may then be permittedto drysomewhat and superposed one on the other with the sheets containin thelarger amount of hexamethylenetetrannn at the top and bottom. Theassembled mass may now be submitted to heat and pressure in a press inthe well-known way to effect the transformation of the condensationproduct into its final condition, the mass being at the same timecompacted into a substantially integral body. The heat treatment shouldpreferably be continued sufliciently to cause the reaction between thephenol resin and the mass so that the hexainethylenetetramin willsubstantially all go into the reaction. The result of such a processwill be the production of a product which is thoroughly water-resistantthroughout, so that if the structure is cut in half or a section of theinterior of the mass is otherwise exposed water or other fluid which maycome in contact with the exposed section will not penetrate therein to amaterial or objectionable extent. The body will have a comparativelythin shell or outer covering which is comparatively hard and which willtake a high finish while the body as a whole may be readily punched,drilled, sheared, etc., because of the fact that the main body portionis considerably softer and more readily macomparatively thin.

It will be noted that the term phenolic substance in the claims isintended to include phenol and its equivalents, as Well as phenolicresins, or phenolic condensation products which are capable of furtherreaction with hardening agents to produlee T e term a hardening reagentin the claims is intended to include substances which will react withphenol or equivalent or with fusible phenolic resins to produce harderand more infusible bodies, such hardening reagents includingmethylene-containing bodies, such as formaldehyde and 'its polymers,-

hexamethylenetetramin, etc., and such substances as acetaldehyde,araldehyde, other bodies having an aldehy e character, etc.

It should also be noted that the invention is not limited to thearticular details of process and construction of the product which havebeen particularly described, but that the same is as broad as isindicated by the accompnying claims.

\Vhat I claim is:

1. A process of producing impregnated material, comprising, impregnatingthe interior portion of a. body of fibrous material with substancescapable of reaction to produce a water-resistant phenolic condensationproduct, such substances comprising a phenolic substance and a hardeningreagent therefor in proportion less than that required, in reaction withsaid phenolic substance, to produce maximum hardness and infusibility,impregnating the outer portion of the body with substances capable ofreaction to produce a water-resistant phenolic condensation product,such substances comprising a phenolic substance and a hardening reagenttherefor in greater proportion than the first mentioned hardeningreagent, and applying heat to cause the reactions between said phenolicsubstances and hardening reagents therefor to ensue.

2. A process of producing impregnated material, comprising, impregnatingone or more laminations or sheets of fibrous materialwith substancescapable of reaction to produce a water-resistant phenolic condensationproduct, such substances comprising a phenolic substance and a hardeningreagent therefor in proportion less than that required, in reaction withsaid phenolic substance, to produce maximum hardness and infusibility,impregnating one or more laminations or sheets of fibrous material withsubstances capable of reaction to produce a water-resistant phenoliccondensation product, such substances comprising a phenolic substanceand a hardening reagent therefor in greater proportion than the firstmentioned hardenmg reagent, superposing said sheets to form a laminatedbody, with said last named lamination or laminations at the outside, andapplying heat to cause the reactions between said phenolic substancesand hardening reagents therefor to ensue.

3. A process. of producing impregnated material, comprising,impregnating the interior portion of a body of fibrous material with afusible phenolic resin and a hardening reagent therefor in proportionless than that required, in reaction with said resin, to produce maximumhardness and infusibility, impregnating the outer portion of the bodywith a fusible phenolic resin and a hardening reagent therefor 1ngreater proportion than the first mentioned hardenfusibility,impregnating one or more lami nations or sheets of fibrous material witha fusible phenolic resin and a hardening reagent therefor in greaterproportion than the first mentioned hardening reagent, superposing saidsheets to form the laminated body with said last named lamination orlaminations at the outside, and applying heat to cause the reactionsbetween said phe- I nolic resins and hardening reagents therefor toensue.

5. A process of producing impregnated material, comprising, impregnatingthe in terior portion of a body of fibrous material with substancescapable of reaction to produce a water-resistant phenolic condensationproduct, such substances comprising a phenolic substance and a hardeningreagent therefor in proportion less than that required, in reaction withsaid phenolic substance, to produce maximum hardness and infusibility,impregnating the outer portion of the body with substances capable ofreaction to produce a Water-resistant phenolic condensation product,such substances comprising a phenolic substance and a hardening reagenttherefor in suflicient proportion to produce a hard infusiblecondensation product, on reaction with said phenolic substance, andapplying heat to cause the reactions between said phenolic substancesand hardening reagents therefor to ensue quite fully, the impregnationwith said reactive substances being sufficient to substantially saturatethe fibrous material therewith.

6. A process of producing material of the character described,comprising, forming a main body portion of sheeted material andsubstances adapted to form a binder therefor said substances including ahardening reagent and a body adapted to combine therewith, forming anexterior portion of sheeted material and substances adapted to formabinder therefor, said substances comprising a hardening reagent ingreater proportion than said first mentioned hardening reagent, and abody adapted to combine therewith to be hardened thereby, and subjectingthe composite material thus formed to heat and pressure suflicient toconsolidate the mass and cause reactions between said hardening reagentsand combining bodies to ensue, the

proportion of hardening reagent in said exterior portion beingsuflicient to'produce a hard infusible surface layer after the finalreaction, and the proportion of hardening reagent in said interiorportion being sufficiently less than that in the exterior portion toenable the same readily to be machined.

7. An article of the character described, comprisin laminations offibrous material substantia ly saturated throughout with a henoliccondensation product, the mass belng substantiallywater-imperviousthroughout, the condensation product being substantially fully reactedthroughout, and the exterior laminations being harder and more infusiblethan the interior-of the mass, and the interior of the mass beingreadily machinable.

8. An article of the character described,

comprising a body of fibrous material strongly impregnated throughoutwith phenolic condensation product, to render the same thoroughlywater-resistant throughout, the condensation product being substantiallyfully reacted throughout, the exterior portion of the mass being hardand infusible, and the interior portion being of a less degree ofhardness and infusibility.

9. An article of the character described comprising laminations offibrous material substantially saturated throughout with a phenoliccondensation product, the mass being substantially water-imperviousthroughout, the condensation product being substantially fully reactedthroughout, and the ex terior laminations being harder and moreinfusible and containing the methylene-containing hardening element ingreater proportion to the phenolic element than the interior of themass.

In testimony whereof I have signed my name to this specification.

KIRK BROWN.

